/in/foo.cc: In function 'char pc(char, bool)':
/in/foo.cc:16:24: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
  return (bj||(*p1++=ch)&&p1==p2)&&fwrite(p1=buf,1,p1-buf,stdout),0;
              ~~~~~~~~~~^~~~~~~~
/in/foo.cc:16:44: warning: operation on 'p1' may be undefined [-Wsequence-point]
  return (bj||(*p1++=ch)&&p1==p2)&&fwrite(p1=buf,1,p1-buf,stdout),0;
                                          ~~^~~~